A modern observer of the starry sky cannot do without one instrument – a telescope. If you decide to buy a telescope, you need to know the basic facts about it, what it is, which types it has, how it differs from other optics, and what usage it can have. Whether you are a professional or a beginner learner of astronomy – regardless of this fact, this device will be a necessary attribute in your luggage.
What is a telescope? A telescope is a device that helps us to observe distant objects by collecting electromagnetic radiation. It is used in astronomy to study the night sky and photograph space things. Galileo Galilei made the first such device in 1609, and it looked like a spyglass in appearance. It is also necessary to understand how such a device works. In its classical form, this is a tube established on a mount – a rotary support device that sets precise guidance to objects of interest. The optical part of the device includes an eyepiece and a lens. These components provide an increase of distant objects, and the degree of magnification depends on the focal length between these two components on the lenses installed there. The most famous telescopes are diopter, catoptric, combined, radio telescopes, and infrared.
• Dioptric – a classic device with lenses, their principle of operation consists of the light collected by the lens from the bodies on the objective lens; the primary condition of work is the coincidence between the focus of the objective the eyepiece.
• Catoptric – the central part is a concave mirror, on which light is collected and reflected on the eyepiece. Such devices have a complete transmission of the light spectrum, and they show all the details of the object under study- color, brightness, depth, etc., but have a limited view.
• Combined devices – combines a lens and a concave mirror. They have a high-quality image and a wider viewing angle than specular telescopes. They also have two subspecies – Schmidt – Cassegrain and Maksutov – Cassegrain. Telescopes of the 1st subtype have a curvature in the center of the mirror diaphragm, which increases the field of view. Still, at the same time, spherical violations and deviations are excluded. Devices of subtype 2 have an optical lens in the focal plane area, which has a convexity on one side and a plane on the back, which makes it possible to compensate for the curvature of the field and avoid spherical deviation.
• Radio telescopes are designed for proper scientific research; instead of optical elements, special antennas capture space signals in a single frequency.
• Infrared – they perceive infrared radiation from objects. In other words, they react to heat, and they are more sensitive; the radiation is reflected on the objective lens and projected at one point, then the sensitive part converts the heat into visual data, and the result is photographed for further studies.
Telescopes differ from other optics in several ways. For instance, a telescope is an optical device with a single viewfinder that allows you to see and interpret distant objects, and binoculars, in their turn, have two viewfinders instead of one, and they are used to observe animals or are applied in hunting; it provides a three – dimensional image of the object as two eyes are used for observation. The difference is that binoculars have a smaller, less powerful wide lens, while the telescope has a more robust lens and a narrower field of view, which can be used for viewing farther distances. You can also compare telescopes and microscopes; the main difference between the two is that microscopes are used to magnify small objects at a short distance, while telescopes are used to magnify large objects at a great distance from us. Likewise, it is worth making it clear how a telescope differs from a spyglass. On the one hand, the spyglass has a lower magnification, a wider field of view, are compact and lightweight, and use prisms in their optical design to obtain a correctly oriented image. On the other hand, Telescopes give an inverted or mirror-symmetrical idea, which is not essential when observing the stars but may be completely inappropriate when tracking animals.
The primary purpose of this device is to collect as much radiation from celestial bodies as possible and to increase their illumination, which allows you to see even dim objects. The second important task assigned to telescopes is to create the sharpest possible image and, in visual observations, to increase the angular distances between objects (stars, galaxies, etc.). The amount of light a telescope can collect directly determines the detailing of the resulting image, from the lunar landscape to the rings of Saturn. This parameter does not depend on the telescope’s magnification, as many are accustomed to thinking, but directly depends on the lens, which collects the light rays; the objective can be either a lens or a mirror, which defines the base of the telescope.
Many of us are connoisseurs of beauty, so we want to learn more and more information about the thing that interests us. Watching the starry sky is an incredible process, which requires a telescope. This device will become your irreplaceable friend, allowing you to know more about space and its components – the stars.